1. The Field of the Invention
This invention relates to an optical position sensor capable of detecting an incident direction of light and its intensity. More particularly, it relates to an optical position sensor suitable for controlling a temperature of air-conditioned air, an air blow-out quantity and a blow-out direction in an air-conditioner for a car.
The present invention relates also to an insolation sensor using the optical position sensor described above.
2. Description of the Related Art
An optical position sensor capable of detecting an insolation direction and an insolation intensity has been used in the past in an air-conditioner for a car in order to optimally control the temperature, blow-out quantity blow-out direction of air-conditioning air in accordance with the intensity of the insolation and its direction.
The optical position sensor of the kind described above is disclosed, for example, in the following references.
(A) An insolation sensor disclosed in Japanese Unexamined Patent Publication (Kokai) No. 63-141816, wherein three light reception sensors for directly receiving solar rays are disposed so as to be directed in mutually different directions.
(B) A solar angle measurement apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) No. 56-64611 wherein tow sensors each comprising a light shading plate having a slit formed thereon and a gray code pattern disposed so as to oppose the light shading pattern are arranged in a manner such that the slits perpendicularly cross each other.
(C) A solar angle measurement apparatus similarly disclosed in Japanese Unexamined Patent Publication (Kokai) No. 56-64611 which comprises a light shading plate having pin holes bored therein and two-dimensional light reception sensors disposed so as to oppose the light shading plate.
However, the light reception portion for effecting optical detection in each of the position sensors (A) to (C) is relatively large, and it is difficult to reduce the size of the position sensors.
In the insolation sensor of the reference (A), three light reception sensors must be disposed in mutually different directions. Therefore, the light reception portion must be formed three-dimensionally, and the insolation sensor cannot be made compact in size. Because this insolation sensor requires three light reception sensors, the cost of production becomes high.
Next, in the solar angle measurement apparatus (B), a gray code pattern consisting of a large number of light reception devices is used for detecting the position of light passing through a slit. For this reason, the light reception portion need not be formed three-dimensionally as is required in the apparatus (A).
However, because the gray code pattern is formed by aligning a large number of photo-electric conversion by aligning a large number of photo-electric conversion devices along the gray code, the light reception portion has a two-dimensional expansion and its light reception is large. Further, because this solar angle measurement apparatus uses two sensors each having a light reception portion having such a two-dimensional expansion that are aligned in such a manner that each slit perpendicularly crosses the other, a light reception area that is at least twice as large as the light reception area of the two gray code patterns is necessary for the apparatus as a whole. Accordingly, it is not possible to reduce the size of this solar angle measurement apparatus. To correctly detect the position of light passing through the slits by the gray code pattern, the relative positions between the gray code pattern and the slits must be correctly adjusted, and this results in another problem that the production rate the apparatus is low.
On the other hand, the solar angle measurement apparatus (C) comprises the light shading plate having the pin-holes bored therein and the two-dimensional light reception sensors so disposed as to appose the light shading plate. Therefore, this apparatus can be made more compact than the apparatuses (A) and (B) described above.
However, because apparatus (C) also uses the two-dimensional light reception sensors, the light reception portion has a two-dimensional expansion in the same way as in the apparatus (B), and its light reception are becomes inevitably large.
Further, this apparatus requires a signal processing circuit for processing the light reception signals from photo-electric conversion devices (pixels) constituting the light reception sensor. However, because a large number of pixels are two-dimensionally disposed in the light reception sensor, vertical and horizontal scanning circuits must be provided in the signal processing circuit so as to scan two-dimensionally the light reception sensor. As a result, problems occur in that the circuit construction gets complicated and the signal processing circuit becomes large in size.
When the signal processing circuit is built into the apparatus, the substrate must have the sum of the light reception area of the light reception sensor and the circuit area of the signal processing circuit in order to form the signal processing circuit and the light reception sensor on the same substrate., and, as a result, the apparatus is large in size.
To reduce the size of this apparatus, it would be conceivable to separately form the signal processing circuit and the light reception sensor. In this case, however, a large number of pixels that constitute the light reception sensor must be electrically connected to the signal processing circuit by individual signal lines. Accordingly, the number of signal lines for the connection becomes enormous, and the assembly work of these signal lines gets complicated and producibility drops.
Accordingly, in the solar angle measurement apparatus (C), reducing the size of the apparatus without lowering the production rate has been difficult.